TV GuideMagazine's winter sci-fi preview goes on sale this week, and here's some of the scoop we rounded up:

• As Smallville races — faster than the proverbial speeding bullet — to its series finale in the spring, familiar faces continue to pop back into the world of Clark Kent (Tom Welling). Even dead people. Lionel Luthor (John Glover), pushed out of a building to his death by son Lex in Season 7, returns to the CW drama on December 3 for the first of four episodes. Then, on December 10, Michael Shanks makes his final appearance as Hawkman and Chloe (Allison Mack) returns, briefly. (She'll be in four more episodes before the series ends.) "It is a great cliff-hanger going into the spring run, because there are a couple of pretty big twists in that episode," says executive producer Brian Peterson. "Things don't go very well for our heroes. Just when Clark is on top of the world, things kind of crash down around him."

• In the November 23 episode of ABC's No Ordinary Family, Jim (Michael Chiklis) suddenly loses his powers and can't figure out why. "He's had a taste of feeling special and making a difference and thinks he can continue fighting crime without his abilities — that puts him in big jeopardy," says cocreator Jon Harmon Feldman. In future weeks, Daphne (Kay Panabaker) comes close to learning what King (Stephen Collins) is really up to, but he and his team have a way of diffusing the threat. Says Feldman: "We'll deepen King's relationship with the Watcher [Josh Stewart] and bring a new supervillain into their orbit — someone Jim and Stephanie [Julie Benz] will end up battling."

• Is Sanctuary's Dr. Helen Magnus (Amanda Tapping) a murderess? Fans of the Syfy series will learn that the kindly, 158-year-old scientist was forced to kill her fellow Oxford student Adam Worth (Ian Tracey) back in the Victorian era. Now this same man — a genius psychopath and the inspiration for Jekyll and Hyde — has time-warped to the present to raise hell. Creator Damian Kindler says, "Magnus must make a deal with the devil because Adam has information about Hollow Earth — an entire world that has been hidden from us for a very good reason."

• In Stargate Universe's mid-season finale (November 30), the team stranded aboard Destiny is finally able to fly the alien ship out of its predetermined path — but that could be a bad idea. "On their way, they find a graveyard of damaged ships from a huge, long ago battle," says Brad Wright, exec producer of the Syfy show. "Unfortunately, their arrival on the scene restarts the fight." Colonel Telford (Lou Diamond Phillips), last seen stranded on a hostile alien vessel, is mysteriously back to help with the dire situation.

• Not surprisingly, life is hell for Supernatural's Sam (Jared Padalecki) and Dean (Jensen Ackles) Winchester these days. Sam's soul is in Hell, under the control of the demon Crowley (Mark A. Sheppard). To get it back, the demon makes the brothers fetch him the "Alphas," the top dogs of each of the monster species — vampires, fairies and shape-shifters among them — that are running amok. So far, it's a bum deal. "The brothers are tired of Crowley calling the shots," exec producer Sera Gamble says, "so [in the episodes airing December 3 and 10], each of them goes pretty far to try to solve Sam's problem." Powerful angels Castiel (Misha Collins) and Balthazar (Sebastian Roche) get involved, as well as Winchester-hating demon Meg Masters (Rachel Miner).

• Over on The CW's The Vampire Diaries, the big reveal about the ancient curse keeping vampires and werewolves on equal ground "really just set the stage for what's to come," teases exec producer Kevin Williamson. In the December 2 episode, Elena (Nina Dobrev) tells overprotective ex Stefan (Paul Wesley) and his brother Damon (Ian Somerhalder) that she can take care of herself now that she knows she is key in the deadly struggle between the supernatural enemies. "Elena's no damsel in distress," says Williamson. To prove it, the feisty teen teams up with fugitive vamp Rose (Lauren Cohan) to try to find the powerful band of so-called Original bloodsuckers.

• As AMC sews up the first season of the apocalyptic zombie hit The Walking Dead, the survivors begin to turn on one another. "Before it's all said and done, the opinions and actions of the group are divided," according to executive producer/director Frank Darabont. "Stakes are higher, dissension develops, rivalries intensify," adds executive producer Gale Ann Hurd, so expect the last two episodes to include shifting allegiances and emotional betrayals. After an attack on the camp, Rick Grimes (Andrew Lincoln) and the remaining refugees seek new shelter. And Darabont reasons, "If I'm in some biological holocaust and I'm in Atlanta, wouldn't the Centers for Disease Control be the first place to go?" Enter the mysterious Dr. Jenner (Noah Emmerich), who Hurd says, "has his own unique perspective on the crisis."

For more on these shows, plus Chuck, The Event, Star Wars: The Clone Wars and more, pick up this week's issue of TV Guide Magazine, on newsstands Thursday, November 18!